Selective signaling system



Nov. 16, 1943. J, T, NElswlN'l-ER 2,334,574

I SELECTIVE SIGNALING SYSTEM Filed Jan. 8, 1941 2 Sheets-Sheet 1 Y 4l/Q ATTORNEY .ww Nm n@ u Jl? u JIJ lli im rlL 1ML FL NOV- 16, 1943- J. T. Nx-:lswlNTER SELECTIVE SIGNALING SYSTEM Filed Jan. 8, 1941 2 Sheets-Sheet 2 INVENTOR ATTORNEY Patented Nov. 16, 1943 UNITED STATES PATENTI oFFicE-q sELEoTivE SIGNALING sYs'rn/M James ',rrNeiswinter, North Olmstead, ohio, asi signor to American Telephone and Telegraph Company, a corporation of New York Application January s, 1941, serial No.y 373,573(

8 Claims.

a selective signaling system using dots and ,I

dashes for selective purposes in which the dots and dashes may be either marking signals or spacing signals.

v.Another object of the invention is to provide aV selective signaling system usingf dots and dashes in which the dots and dashes comprising the code may be formulated from teletypewriter code combinations. I

A still further object of the invention is to produce a selective signaling system which may be used in connection with teletypewriter circuits, manual telegraph circuits, signal circuits for telephone circuits and circuits for remote control of equipment of all kinds.

The invention may be more fully understood from the following description when read in connection with the accompanying drawings Figure 1 of which shows a selecting circuit adapted to be operated by dots and dashes produced manually, While Fig. 2 shows a modication in which the dots and dashes may be produced fromrteletypewriter code combinations. In the circuit of Fig. 1 the dots and dashes are marking signals, while in Fig. 2 the dots and dashes are spacing signals.

Considering rst the arrangement of Fig. `1, four selecting relays are employed which by various arrangements of'operated and inoperated conditions of the relays permit a total of sixteen combinations to be selected. By adding an additional set' of selecting relays to the chain it will be obvious that the number of combinations may be doubled. In the arrangement of Fig. 1 the code for setting up a selective combination consists of four units either dots or dashes. These four units, as already stated, are marking signals, and, of course, are necessarily separated from each other by spacing signals.

In the arrangement of Fig. 1 the operation and non-operation of the selecting relays is accomplished as follows: The iirst opening ofthe telegraph circuit to which the equipment is connected produces a spacing signal which makes the first selecting relayof the chain available. If it is desired to operate this relay, a long marking dash is sent. If it is not desired to operate the relay, a marking dot is sent.4 In either case the relay is then` disconnected from 4the transmission circuit and the second selecting krelay isv prepared. The sending of a longdash willnow operate this second relay, but if a dot is'jtrans-4 mitted, the relay will nOtoperate. In either case the second relay is disconnected from the circuit and the third relay is presented. This cperation is continued until four marking dots or dashes have been transmitted.'k The last marking signal, if a dash, operates the fourth selecting relay, and if a`dot,rdoe`s not operate the relay. f p

After the, last dot or Vdash is transmitted'xa iifth relay isv connected into the chain. This iifth relay performs certain functions including the final operation of the selected element. The fourth marking dot or dash ofthe -codecombination is, of courseQfollowedrby an open cir` cuit or spacing signal after which the rcircuit would normally be closed to transmit a continu` ous marking signal. The sending of this iinal marking signal after the fourthv dot or dash is transmitted operates Vthe fth relay which in turnv operates the particular-element that had been selected by the selecting relays. If, however, instead of iinally closing the circuitthe operator sends a fifth dot, the space following this fth dot operates a relay which locks up and prevents any further functioning of the equipment until it has been cleared out by again closing thevcrcuit for a period of aboutA at least two seconds, this period being longer than the normal selecting dash of the code combination. Thus even if a, combination is set'upin the equipment the sending of` a single additional dot will prevent the equipment from operating. Y

The operation ofthe selected element, which in the circuit illustrated is a relay, will `result in the operation of another relay which functions to open and close the telegraph circuit over which the signals were 4sent at a rate of about twice per second. The Ysteady clicking,` thus produced on-the circuit indicates to the sender that the selected equipment is operated, and also serves to hold the circuit for the sender until the called office hasY answered. Opening the circuit at either the sending or called cnice or at any otheroiice connected in the same line, causes the clicking to cease and selected relay to release, and arranges the equipment so that the next two second close of the circuit will result in a release of all of the relays and the restoring of the equipment to its normal condition for receiving any selection.

Referring to Fig. 1, at the left the terminal T indicates a transmission line which may be a telegraph line for either Morse or printer operar tion, a telephone line, or other type of signaling circuit. This terminal includes a line relay L which responds to marking and spacing signals and thereby controlsthe selecting operations to be hereinafter described. The armature of this relay is normally on its marking contact. When shifted to its spacing contact it operates` a. slowrelease relay D to shift the armature of said latter relay from its normal' marking contact to its spacing contact, thereby in turn closing.V the circuit of a slow-release relay G which applies a controlled" ground' to' the various' relays' in" the selecting chain' about to` bei described. Y

The' selecting relay circuit consists of archai'n' of five sets'fof' relays; each set consisting of three relays. A The first. four' sets ofr three relays' each set upthe selection', while the fifth set of' three relaysy effects the final' operation of the selected lease relay I. Consequently in the normal condition with the line circuit closed, no ground is. connected tov any of the chain relays. The relay G is operated, as will presently appear, upon the initiation. of the selecting operation. But if` any time it should be released either during or after the selecting operation, the ground which it supplies to each of the selecting relays will bedisconnected and all of the relays of the chain element and performs A,certain other functions which will; be describedv later. They first setv of relaysof. the chain consists Vof relays I A, IIB and ISI` Thesecond'set consists'of'relays 2A, 2B,` 2S, etc., the iinal's'et of'three relays being designated GA-,YSB and GSI VThe A relaysfo'f the chain. are connectedY to, the rriar'king contact of thev line relay L arid areY operated by any marking signal regardless of'whethe it is.a dot or dash. The. S relays. however, ,are controlled overv the marking contact of' the slow-release relay D, and are, therefore,.only operated when the line relay L transmits'. a.. markingv dash. The B relays are echcontrolled by a contact of the corresponding A relaysA aridare operated by the spacing signal following each` dot or-dash to shift the selecting circuits from the rst set of relays of the chain4 to the succeeding set'of relays.

Thelast set ofrelaysfof the chain designated 8A, SB'Va-nd SS effect the final operation of the selected device and perform certain controlling and. other functionssue h as the operation of the slow-release relay Iy whichsends a clicking or answer-back signal after the selection has been completed". The four selecting S relays'by means of their armatures setup operating circuits through anyone ofy a number of nal selectedi. relays "I,; 2,. 3,1 4;.' etc. These selected relaysi as' shown are nine' irr number', but actually may be as manyi as' fifteen..` Theoretically a sixteenth relay' could. be` provided but this would involve using. a selective' cod'e consisting of four dots, and asv this combination might beproduced in ordinary Morse; itiis-bestnotto attempt to selectA a sixteenthi'relay.. It will be noted" thatthev final' selected!relaysillustrated are not actually shown connected inthe selecting circuits, but the letters- A-E, A-F, etc., atthe terminals of eachr of: various windings indicate that the terminals of the windings are tor be connected across the correspondingly lettered terminals' in the finaliv selecting circuits: controlled over the armatures of relays' 2S and 3S.

Further details: of this circuit` will be. understood'l from they following. description of its opA eration.

Assuming, thatv the. line circuit is normally:

restored to normal.

In' order to send a dot or dash, the operator must-iirst operate his key to momentarily open the circuit thus sending a space signal. The armature of. the line relay is thereby shifted momentarilyto* its spacing contact S, thus operating the slow-releaseY relay D, which inturn shiftslits armaturefrom its marking to its spacing; contact and operates the slow-releaserelay Gtosupp'ly the ground' connection for all of the chain relays.

'The circuit is now-in condition to receive the first selecting impulse' which is sent by closing the telegraph circuit T. This operates'the'line' relay- L to its markingcontact, thereby closing a circuit from positiveV battery, markingA contact of relay L, upper back contact of relay IB,'wi'nd ing of-l relay IA and thence to ground` over the closed contact of relay G. Note that in tracing this circuit'- and otherV circuits hereinafter described; the winding of eachrelayj and the' armatures-and? contacts controlled' thereby' are enclcsed within` a dottedv rectangle' to avoid confu-v sion between contacts of different' relays.. Relay IA 'atonce locks up' over its right-hand front Contact` to` positive battery, and at' its left-hand frontv contact prepares a'circuit path for the operation of the relay IB.

The relay IA operates upon a marking signal regardless of its' length, since it is operated over thel marking contact of the' quick-operating relay L. Whether or not the actual selecting relay' I S'Visoperated or not depends upon the length of thejmarkingsignal'. If the marking signal is merely a dot, the relay D being slow to release, willjnot'shift its armature from its spacing to its-'marking contact, andv no circuit will be closed for' the relay IS. If, however,the marking impulse sent over thetelegraph circuit is for the length of a long dash, relay D will release and shift its armature to its marking contact, thereby completing a' path for relay IS from positive battery, over the marking contact of relay D ljower back contact of' relayv IB, winding of relay I'S and thence to ground over the contact of relay G. Relay G is, of course, a slow-release relay and', therefore, holds. itsV controlled ground appliedV tothe variousA selecting relay circuits for such length' of time as' is' required for the slew-acting relay D to release, and thereafter for 'the' slow-acting relay' G to release. This period is substantially' longer than the length of' anyy dash that is to 'be transmitted'. If' the closeofv the telegraph circuit' is for a period' of approximately two seconds, however, relay G wouldiaflso release', thereby causing relays IA and IS to release, so that the circuit would be cleared.

Let us now assume that either a dot or a long dash hasbeen transmitted, and if it was a dash, that the dash was not long enough to cause the relay G to release. Upon the completion of the dot or dash a spacing signal is sent over the telegraph circuit which brieily shifts the armature of the line relay L from marking to spacing. This completes a circuit Vfor 'the relay IB from battery over the spacing contact ofrelay L, over conductor 22 to the lower contact of relay I, over right-hand back contact of relay BS, over conductors 2I and 20 to the left-hand makecontact of relay IA, through the middle normal contact of relay IB, winding of relay I B,and thence to ground over the make Contact of relay G. Relay IB now locks up overv an obvious circuit at its middle front contact, and at its upper front contact transfers lthe circuit over the marking contact of the line relay L from relay IA-to relay 2A. At the same time its lower armature spacing interval is transmitted, relay L over its` spacing contact completes the circuit as previously traced to the conductor 20 and thence over the right-hand front contact of relay 2A and over the middle normal contact of relay 2B through the winding of said relay and thence over thev make contact of relay G to ground. Relay 2B is thereby operated and locked up and shifts the circuits over the marking contacts of relays L and D to relays 3A and 3S, respectively.

The third dash or dot transmitted 'over the telegraph line operates the relay 3A, and in the case of a dash the relay 3S is operated, and these relays are locked up over obvious circuits. Upon the completion of the third dot or dash, the armature of the line relay L is shifted from marking to spacing, thereby operating the relay 3B over a circuit previously traced to conductor, thence over the left-hand front contact 'of relay 3A, middle normal contact of relay 3B to ground over the contact of relay G. Relay 3B is locked'up and transfers the connection Vover the markingcontact of the relay L from relay 3A to relay-4A. At the lower contact of relay 3B the circuit from the marking contact of relay D is shifted from relay 3S to relay 4S.

The fourth Ydash or dot transmitted shiftsV the armature of the relay L to its marking contact and operates the relay IIA over the upper make contacts of relays IB, ZB'andV 3B in series, and over the upper back contact of relay 4B. In casey the marking signal is a dash, relay D falls off and completes a circuit for relay 4S from its markingA contact, over the lower front contact of relays IB, 2B and 3B in series, and over the lower back contact of relay 4B to selecting relay 4S. Relay 4S now operates and immediately locks up. At the end of the fourth dot ory dash relay L shifts to its spacing contact and operates the relay 4B over an obvious circuit including the left-hand make contact of relay'4A. Relay 4B transfers the connection over the marking contact of relay L from relay 4A to relay 6A. At the same time the connection over the'rriarking `four of the Srelays.

contact of relay D is shifted from relay 4S .to relay SS. f r A This completes the selecting operation, and the individual relays IS, 2S, 3S and 4Sare either operatedV or notoperated, depending upon Whether dots or dashes were sent atthe time they were connected incircuit. The combination set up on these relays through their variousy lower armatures hasv already determined which ,relay of Vthe nal group of relays I, 2, 3, 4, 5, etc., is to be selected by a circuit which-willy be hereafter described.Y I

At this point several different conditions may arise producing diierent results depending'upon what the sending operator does. Normally after sending a short space at the end of the fourth marking signal the sending operator will nally close the telegraph circuit, thereby shifting the armature of relay L to its marking position. This operates the relay 6A over the'four upper front contacts of relays IB,v 2B, 3B and 4B. If as would normally be the case, this marking condition continues, relay D will, after a short interval, release its armature to its markingr position and operate the relay BS. Y Y

Relay SS in operating will, at its left-hand front contact, place battery on a selecting circuit which depends upon the code combination which was sent, and will thereby operate a selected one of theiinal relays I, 2, 3, 4,15, etc. f These nal relays are variously connected to the contactsof the relays 2S and 3S, so that; a diierent relay will be operated for each setting. For example, final relays I, 2, 3 and 4 have their upper terminals connectedy to the A terminal'of relay 3S, while the opposite terminals of the windings of the relays are connectedrespectively to the terminals E, F, G and H of the relay 2S. Similarly relays 5, 6, I and are connected from terminals B of relay 3S to theterminals E, F', G and H, respectively, of relay '2S. Final relay 9 is. connected from terminal C to terminal E, and so on for any other relays of the iinal group which may be provided.

Let us'now assume that the code transmitted was four ,dashes resulting in the operation of all A circuit4 for relay I will be completed from battery over the left-hand front contact of relay BS, over the make contact of the lower armature of relay 4S, make contact of middle armature of relay 3S, terminal A, throughl the winding of iinal relay I, terminal E, make contact of the middle armature of relay 2S,

, make contact of lower armature of relay IS, and

thence to ground Vover the lower right-hand back contact of relay 6B and the make contact of relay G. Relay Ijis now operated and locked up at its left-hand front; contact. This contact also supplies battery to a controlled auxiliary circuit I to perform any signaling or otherdesired operation. VItmay'be noted in passing that the selecting circuit for the relay I does not close rimmediately after the relay'Dshifts its armature from spacing to marking, because the relay SSis slow to operate and requires a brief interval before its armature pulls up., The purpose of this delay interval will appear later. y

When relay I is operated it completes a circuit for the slow-release relay I from the marking contact of relay D, over' the front contacts of the lower armatures of relays IB; 2B, 3B and IIB, over the left-hand back contact'of relay 6B, through the Winding of relay I, over the right-hand front contact of relay I, and thento ground .over the make contact of relay G'. Y The operation of the relay I at its upper right-hand nfror'it contact opens the telegraph circuit T. This, ofcourse; occurs after an interval long enough to permit the armature ofthe relay .D to shift toits mark# ing contact after the final closing of the telegraph circuit Tby the sending operator, plusthe time opening of "the telegraph circuit by the upperV right-hand contactr of relay I results in'shifting the armature of relay Lto its spacing contact,

whereupon relay D is at once energized and shifts its armature from its marking to its'spacing Contact.. This removes the batteryfat'the Y marking contact of relay D from the relays BS and I.' Relays GS and I are temporarily released, and the upper right-hand contact of the latter again closes the telegraph circuit. This results in shifting the armature o-f relay L to its marking contact so that relay D kafter a, vmoment releases and shifts its armature to its marking contact, thereby again completing the circuits of relays GS and I, vas previously traced. Relay I being again operated once more opens the telegraph circuit and the cycle just described is repeated resulting in a steady clicking on the telegraph circuit.

It will be noted that the closing of the telegraph circuit whi'ch occurs when relay Ireleases is not long enough to permit the relay G to release and remove the controlledV ground from the various selecting relays. It willalso be noted that when the upper right-hand contactof'relay I opens the telegraph circuit so that the armature 'of relay L is shifted to its spacing contact, the circuit which would otherwise be'completed over said spacing Contact to the conductorZO to operate the relay'B will beheld'openby'the lower right-hand contactof the relay I, thus preventing .relayf 6B from operatingunderthe conditions producing the clicking operation. The right-hand contact of relay BS, which like the lower right-hand contact of relay I controls the circuit for relay 6B, functions to hold the circuit of relay 6B open for a brief period after the contacts of relay I have closed. This period is long enough to allow the armature of the relay L to leave its spacing contact and hence prevents operation of the 6B relay immediately Vafter the relay I closes its contacts. This action is'due vto the `fact that the relay BS is slower to release than the relay I. l

The clicking operation above described results in the line relay L operating periodically in time with the relay I. As shown, the final relay selected (in this case the relay l) is locked. up by its own left-hand armature over a, circuit to ground previously traced from the terminal E'of its winding and overcontacts of relays 2S,l IS and 6B to ground over ythe contact of the relay G. The selected relay, therefore, remainslocked up during the clicking operation andV remains locked up so long as relay Gis operated and the relay BB is not operated. YHowevenif desired, the locking contact for the final relays may be omitted in which case the selected nal relay will also operate periodically with relays BS and I during the clicking operation.

7 If the operatorshould hold the telegraph circuit open during `the time the clicking operationis occurring, the line relay L will fall off to its spacing contact and thereby energize the relay D which shifts its armature to its spacing contact where it remains so long as the open continues.V This ,of course, releases the relays GS and I and a circuit is consequently closed to operate the relay BB over the spacing Contact of the relay L, over lower right-hand contact of relay I, right-hand contact of relay SS to conductor 20, and thence over the left-hand make contact of relay 6A, Aupper normal contact of relay 6B, and through the winding of said relay 6B to ground over the contact of relay G. The relay 6B at its lower left-hand contact opens the circuits of relays GS and I, and at its right-hand lower contact opens the locking circuit of the selected relay I. Relays BS and I will be released and cannot again be operated until a new selection takes place. The selected relay I is also restored to normal. If following this opening of the telegraph circuit by the operator the telegraph circuit is again closed for a period of about two seconds or more, rthe relay G will release and remove the ground connection from all of the A, B and S relays, thus restoring them all to normal so that the circuit is now ready to receive a new selection.

If after the operator has transmitted the four dots or dashes which determine a selection, the operator instead of closing the circuit permanently merely closes it long enough to transmit a clot, the relay 6A will be operated, but the relay ES will not be operated as the sending of a dot does not permit the slow-release relay D time to shift its armature to its marking contact. During the spacing impulse following the dot the relay 6B will be operated over the spacing contact of the line relay L, lower normal contact of relay I, right-hand contact of relay GS to rconductor 25J and thence over the left-hand contact of relay 6A, upper normal contact of relay 6B, through the winding of said relay and over the contact of relay G to ground. As a result no final relay will be selected because the relay 6B prevents relay BS and I from operating. No final relay can be selected until the circuit has been closed for two seconds or more to allow the relay G to release and restore all of the apparatus to normal, so that a new combination may be transmitted and recorded. It Will be noted that the relay 6B is operated during the open circuit following the dot. There is no possibility of a nal relay being selected before the relay 6B operates under these conditions for the relay BS is slow to operate and thus delays the nal selection for a brief interval.

As already stated, by using dots and dashes sixteen code combinations are possible with this circuit as follows:

The first of these combinations, which consists of four dots, is preferably not used because of the possibilitythat such a combination would result from ordinary Morse signals and thus cause false operation. v

False operation of the equipment byMorse signals is made very improbable by the following conditions which must be met to make the equipment operate:

r1. The circuit must be closed for at least two seconds before a combination is sent.

. 2. Each of the combinations (except the rst) hasatleast one dash in it, and is made of a length considerably longer than the dashes sent in normal Morse operation. The dashes used in Morse operation are too short to allow the relay Dto release to marking and thus operate an S relay.- As is well known, the marking intervals of Morse signals are rarely more than half Ya second in length.

3. Only fourdots or dashes are Vsent after which the circuit must be closed for about two seconds or more in order to operate the selector. The sending of even a single dot after the four dots or dashes of the combination have been sent prevents the equipment rOmoperating and the operator will know that the selection has failed because theanswer-back clicking signal does not occur. Y

4. After a Morse signal is sent over the circuit, the rst ve dots or dashes of the Morse message go through the relay chain and lock up all of the relays including `the relay 6B so that no final relay can be selected. The S relays will not be operated during the sending of the Morse message because the dashesv of Ythe Morse message are too short. The relays of the selector Will remain in this locked-up ,condition until ,theV

telegraph circuit is closed for approximately two seconds, and this conditionv will not normally ocl selecting signals are sent over the circuittheA problem of avoiding false operation, of course, does not exist. i In such cases the equipment may be operated on short vand longimpulses producedY bya push buttoninstead of a telegraph.. key.

i Instead lof sending the dotsl and dashes manually by means of a telegraph -key or push button, it -may be desirable in someinstances to use a dial transmitterof the type used in telephone machine switching, in orderito make sure that the timingA intervals are correct. For example, the dial'fmightbeso arranged that by dialing digit 1 a' short mark orspace would be transmitted, and by dialingV digit 5 a long mark or space would be sent. Thusinsteadof a code comprising dash-dot-dot-dash fora selection we would simply' dial 5115.` For operators who work everyday on a circuit of this type, the manual method of signaling with a telegraph key is so simple, and the proper length of dash is so easily obtained,.1that no accurate time `control device such as .ai dialv is necessary. g.

-With thesystem as described using the code, four short and long signals, a total of sixteen different selectionscan be madeiiifteen if we omit the our-dotcombination). If we use five long or short signals the number of selections may be doubled, as the-number of possible combinations open circuit conditions rather than marking Vin-V tervals. ,The circuit may be also, modified in a tively to operate or to pass by each of theiour4 selectingrelays, and no answer-back or acknowledgment signal is included in the circuit. 'Ihe length of the long spacerequired to operate a selecting relayjmay be `obtained fromthe teletypewriter code corresponding to the letter yT, and the length of vtheshort space required to passby a selecting relay without-operatingit may be obtained from the teletypewriter code corresponding-to the letter V. u i i The normal teletypewritercode consists of 4an open circuit starting impulse, normally about 22 thousandths of a second in length, followed by live character determining impulses each about 22 thousandths of a second lonrg, these :in turn being followed by a yclosed circuit stop impulse whose length is about one and one-half units, or 33 thousandths of a second, making a total of about 165 thousandths vofasecond.l TheI five character determining impulses may beiv either open orgclosed circuit impulses dependingupon the character tobe printed. i s t;

The letter V is well adapted to transmita short space signal, since-its group of five character determining impulses consists of one open circuit impulse followed by f ourA closed circuit impulses. We will then haveganjopenvcircuit im,- pulse fortyfour seconds longlconsisting .otthe start impulse and the ,vrstcharacter `'forming impulse of the letter .v Vr This will be followed b y four closedmcircuit `impulses comprising the remaining characterv determining impulses and the stop impulse of aboutf33V milliseconds, ora total elapsed time of 121 thousandths-of a second for the closed circuitcondition.y Similarly the use of the 'I- combination forthe'long open circuit or dash impulse gives an open circuit start, im-

pulse followed by four open circuit characterV forming impulses making a vtotal open dash of thousandths of a second. This is followed Y by a closed circuitcondition consistingof one character forming impulse andthe stop impulse,

lector circuit. Consequently no acknowledgment or answer-back signal need be.` provided. Protectionrfrom operation by normal Teletype signals is obtained. by requiring eitherA a break" signal or a blank character signalY to be transmitted over the circuit to make the selector circuit ready to receive a combination. A break is anopen circuit condition which may beuontinued any desired length of time. Y A blankis a teletypewriter signal all of the unitsl of which are open circuits except thermal Stop impulse. A second break or blank signal-is transmitted after the combination has been sent, in order to operate the particular 'relay that -has been selected. i i 1 The break signal is, of` course, longer than the entire combination for any particular Teletype character, and ordinary slow-actingor slowrelease relays' are 'sumcient todistinguish between the codeselecting signal and the break signal. A blank signal in a teletypewriter is simply the signal sentV whenv nothing is being printed, and this consists of an open circuit condition for about `132 thousandths of Ya second followed! by a closed circuit stop signal. In order to distinguish between the blank-space' of 132 thousandth-sof a second and the T` space of 110 thousandths of a'second, the slow-operating or slow-release transmitter and that the circuit is normally closed. It will be notedthat the marking and-I spacing vcontacts of the linerelay-L and the-slowrelease relay D are reversed with respect to Fig. 1, so-thatthel'spacing con-tact of the-line relay is connected to the circuit operating the A relays, and the'spacing contact ofthe lD relay is connected to the circuits operating-thesrelays. The relay G has two contacts, one of which controls the application of ground to` the A relays in one position and-to-the-iinal selecting circuit for selectinga final relay in its other position. The-second-'contact controls the connection ofground-i tothe B` and S relays.v

With the line circuit closed the relay L is energized so that* its-armature rests on its marking contact. The relay Dis, therefore, normally. energized so'that its armature is on its marking contact; and it in turnl completes the circuit to the relay G, which is alsonormally energized. Under these conditions vthe VAyB# and S relays may be either operated orfnon-operated, depending upon vwhat may have happenedin the line circuit prior to its closed-circuit condition.

If now a-break signal is sent ofsufcient lengthto allow the D and 1G relaysto release,- the- G- relay at its left-hand contactdisconnectsground; from the'windings of the A-relaysand releasesr any that may have-been operated.- The B-and S relays, which Vnormally obtaintheir ground from `the left-hand-contact of the IA relay, are not released'during the break signal because of the ground connected to their-windings over theright-hand back contact of the relay G in-i-ts-released position. The close of the Teletype circuit followingthe-break againoperates the L, D and G relays. Since the relayL IA was previously released and thel G relay-is now energized so as to open its right-hand contact, lground is removed from the windings ofv any B and S- relays that might have been operated. 'I'he circuit isnow entirely cleared and is ready toI receive -a code combination.

If now a Teletype transmitter is operated toy send the combination of letter-'I'4 into the circuit, the long space of the character will operatethe relay IA over a circuit from battery, over the spacing contact of the line relay L, upper back contact of'relay IB, through the-'winding of relay IA and over the normal operated contact of the relay G to ground. Relay `IA at once locksup over its right-hand front contact. At-its extreme left-hand front contact relay IA placesground onA the conductors leading to thewindings of the Bl and S relays. At its middle front contactrelay I-A prepares a patli for the opera-4v tion of the relay' IB on the marking signal fol"- .lowing the space.

The space of the T signal is long enough to allow the relay D to release to its spacing condition, but is not long enough to release the relay VGr. The relay D, upon shifting its armature to f signal is transmitted, but itdoes not operate if a V signal is transmitted.- The marking condi-- tion following the space of the letter T or V oper-- ates relay I'B by shifting the armature of the line relay from its spacing to its marking contact. This completes a circuit from batteryV over the marking-contact of the relay L, overl the' middle front contactl of relay IA, middle normalh contact of relay IB, winding of relay I1B',and1over the extreme left-hand front contact of relay IA Y to ground.

The operation of relay IB prepares-the path-ta operate relay 2A on the next spacey regardlessof its length, and also-to operate the relay 2S, if the next space is a long one. Thus the space of the next character operates relays 2A and` 2S,r if the character transmitted is a T, but only vrelay 2A is operated if it is a V.n The mark following the above space operates the relay 2B-,. which in turn prepares the path for the operation of the relay 3A and the possible operation'A of the relay 3S.

The space of the third character operates relays SA and 3S, if a T is transmitted, but only the relay 3A is operated if the character is aa V. The mark following the above space operates the relay 3B, which in turn prepares the path for the operation of the relay 4A and the possible operation-of relay 4S.

If now a T is transmitted, the space thereof.

if operates the relays 4A and 4s,..but1f a v is transmitted, only the relay IIAv is operated. The; marking conditionV of the relay'L following the: above space operates the relayl 4B, which; prepares a path for the operation ci the relay SA,v

and for the possible connection of battery fromr the' armature of the relay D to the lower armature of the relay 4S,`the latter circuit extending over the lower back contact of relay BB.

A break signal (longer than the dash assuciated with the character T) will first release the relay D so that its armature is shifted to its spacing contact. Battery is now connected over A the spacing contact ofthe relay D andthe lower front contacts of relays IB, 2B, 3B and; 4Bk in series, and` over the lower back` contact ofi relay 6B to the selecting circuit determined. by the; lower armatures of the selecting relays. IS, 2B; 3S and 4S. This selecting circuit,- however, is still open at the back contact of relay G.

However, if the break signalr persists foi'. arperiodsubstantially longer than-,the openv circuit, condition of the character T, thev relay Gi will. in turn release its armature. and place ground4 on the lower armature o1'v selecting relay IS.

This results in the operation of one'otthenal.

relays of the group I, 2, 3, 4, Ii, etc.,` depending upon which one was selected by the combination set up on the S relay'armatures. If

all four of the S relays were operated,.there1ay I, which is connected across the'k terminals` A and E ofthe armatures of the relays- 2S and 3S, will be voperated and locked in this position. The manner in which therelay I is locked is obvious fromthe circuit diagram. The locking circuit offrelay I `is independent of the selecting circuit. It.` will, therefore, remain locked .up until some attendant releases it. The left-hand front contact .ofthe selected relay I may be used forr any desired purpose, such asA` closing a circuit to some element performing an operation in 'the test room or in a customers oiice;V

The release of the relay G o'n the linal break signal also resulted in releasing the A relays by removing the vground `from their windings at the lefthand front contact 'of said relay G. The B and S'relays `'remain operated, however, despite the release of the relay IA because of the ground connected to the windings of these relays .over the right-hand back contact of relay G.' The B and S relays,.therefore, remain operateduntil the G relay :is again energized when the. circuit is. again closed at the end of the break signal. This permits the operation of the iinal relay ofthe group I to l5, inclusive, before the B'and S 'relays are released.V Relay IA is of the slow-release type, so that it will hold ground on the B and S relays until'the G relay has completely released and placed ground on these relays. By holding the B and S relays up until the' G relay is finally reoper'ate'd at the close ofthe break, the selection and operation of the 'final relayof the group I to'I5 is completed before the B and vS relays are released.

We have just'seen that when; four selecting space characters have set up a combination in the selector circuit,'and these are followed by a break signal long enough to'permit the relay G to release, a selected one of the final relays-of the group Ito I5 is energized due to the fact that the relay GWhen released applies vground to the lower armaturer of the selecting relay IS. If, howevergafter sending'four singlespace char# acters-to set up a combination in the Vselector circuitth'e operator should: discover that'he had sent thel wrong combination, he may prevent the ycombination from being* `eiective by sending a frth space lcharacter, either afV-orna T. As neither o f these jcharactersiopens the line circuit long.' enoughlto,,permitiltheffrelay 'Gl'to all olf,

the relaysjSA and 6B,` will` be, (operated, Aand, Athe latterat, `its','lower contact prevents the Yclosing of .the operatingcircuitjfor 'the A.selected Afinal rela'yff A The circuit for operating the rela'y 6A is closed when the ff-th character causes thefline relay L to #shift ,its armature .toits spacing contact, Vthereby connectingl battery over the four upper contacts/of the relays( IB to 4B, inclusive, and

through the winding of the :relay 6AY to ground :6 0

over the left'fhandmake contact of the relay G. Relay ,6A locks up, and as soon as the space comes to an end and the marking condition be- Agins,gthe `line relay L shifts its `armature to its 'marking contact,V thereby Yconnecting battery over the lefti-hand make contact of relay 6A, through the upper normal contact of the relay 6B, to ground overthe left-handfrontcontact of the relay IA. .The relay 5B is locked up at its upper front contact. and, as already. stated, lat its lower contact it opens the operating circuit for theflnal relay which *would otherwise have 'been selected.I It'will nowbe'irnpossible to complete a circuit for anyof thermal"y relays until a break sigrialhas been' sent to clear the-relays,

and thisvin 'turn has been followed by sending a new combination. A i 1 By using the characters V and'T to obtain the short and long spaces, each combination consists of four characters. The circuit, however, can bedesigned' to operate von alshort space of 22 thousandths of a second and a'long space of 66 thousandths of asecond. If this is done, itis possible to obtaintwo spaces from one character. For example, We might chose a'character having two short spaces; orwe might choose. archaracter having one short spaceY in the rst part/of the code and a longer space in the latter part of the code; or welniay iinda'character in which this arrangementis reversed .with thelong space in the early part of thecodeand theshortspace in thelatter part. By using such characters' the number of. characters which must actually .be rsent for each selection may be reduced to two characters for .nine of the combinations and three ior six ofthe combinations. For example`,ithe characterK can be usedV to provide two shortspaces. 'The`y character E may be used to' providea short' space and along space, and the'cha'racterN may be used-toy pro-A vide a long space and a short space.. For Lthe sixteenth combination whichY requires four Acharacters, either T, O or .M, would be available to provide a single longl space, and-the one to be used might be determined by the location of the othercharacters of the combination on the Teletype keyboard, an "effort being made to keep the characters near. each other. In the chart below one column gives sixteen -combinations on the basis ofzusing thecharacters V and'. T for select# ing purposes.` Inithe succeeding column lthe-.cor-

responding combinationsof charactersare Ygiven using two yspaces per character fin certain 1instances. The use ofthecombinations shown in the nalfcolumninvolvesno changein -the prin- -ciple of theiselecting circuit. f- It merely involves a change -in vthe timing'offrthelslowrelease relays sary. '-.vAn'answer-backsignal maybe provided',

however, ina very simple manner by rnerely prof viding means to send al short Aopen signalfrom the selector fcircuit into `the Teletype circuit-T after the nal relay'desiredhasbeenselected. This would bereceived'on the :typewriter machine vat the sending station. asian M or: an O, thus indicatingvthe operation of the selector,

It Willbe obvious that the general principlesV herein disclosed maybe embodied in 'many other organizations Widely different from those illus` trated Without departing from the .spiritrof the invention as den'ed inthe followingclaims.

`What is claimed is: I l "1. In a signaling system, a signaling circuit over which various selective signaling codes each consisting of the'same iiiredjnumber oflunitsmay be sent, each code unitbeing either a dot or a dash .so that the total number of .codes possible will be 2l1 Where n is the number of `code .units'in each code, then dashes of each cf said codes being of an order of time .durationniaterially diierent from lthe usual dashes .of a Morse code :and from a normal succession of units of a teletypewriter code, a selectivelapparatus for making va plurality of different selections of elements to-'be selected by means tof a corresponding .number of said codes, said selecting apparatus including 'a plurality of sets of selecting relay apparatus, one set 'for each :code unit of a code, means responsive to said code units, whether dots or dashes, :to successively connect said sets of selective `relay apfparatusfto. said signaling circuit .as ysuccessive units of saidselectivesignaling code are transmitted, means whereby .each set .of selectingA relay A,apparatus may determine part ofga final .selection of fa desired one Vof :said elements tov be selected in accordance with Whether thecorrespending signal element isa dotv ora dash,.means to complete said final Y selection. and means whereby .the ,person sending any selective 'signalving code vmay defeat said nal selection after the lapse of a time period of Yany 'length following the iast unit ofthe code.

2; 1n a signaling system, a :signalingxcircuit over which various selective signalingy .codes each consisting ofthe same xednumber of units `may be sent, each code unit Vbeing eitherxa .dot or a dash so that the total .number of codes possible will Vbe 2n Where n is the numberof codeunits in each code, the dashes of each of said-scories :being .of Yan order vot time durationmaterially difconnecty said. sets of 4.selective relay .apparatus toY transmitted, means whereby each set .of selecting.' .relay apparatus `may .determine part ofl a final selection of .a desired one of said elements tof-be selected in accordance. With `whether the corresponding signal element isa dotor a, dash, means'to complete .said final selectiomjand means to defeat a final selectionin accordance with any selective signal code' received unless said selective signaling codeA is :followed by 1a circuit condition .of the same character vas the units of a selective signaling `code :but of an order of time magnitude materially diilerentv from that of said units. y 1

4. In ay signalingysystem,v a signaling circuit over which variouslselective signaling codes each consisting of the same -fixed number of units may be sent, reach, code unit .being Aeither .a .dot v.ora dash so that .the total number l,of :codes vpossible Will be 2f? where-:n :is the number of code Aunits -in each code, thedashes of,` each of said-codes being of an order .of time dura-tion materially different from .the usual .dashes .of :a Morse code, va selective apparatus .forrmaking a plurality -of different selections of elements to be selected'by means of a corresponding number tof said vcodes, said selecting apparatus including .a plurality of setsy of selecting relay apparatus, one set for each code unit. of a code, means responsive to ysaid code units, whether dots or dashes, to successively connect saidsets of :selective relay apparatus to saidsignaling circuitas successive units of said selective signaling codeare transmitted, means whereby each set yof .selecting relay apparatus may determine part of a nal selection lof va, .desired cneof said elements ytorbe selected in .accordance with whether the corresponding signal element is -adot or .a =dash; meansto complete said nal selection, and -means to defeat a nal selection in accordance with anyselective signaling code received unless said selective signaling lcode' Vis followed by a circuit condition of -the samecharacter as theunits of a selective signailing code but of an Aorder ottime-magnitude said signaling circuit as successive unitsof said selectivev signaling code are transmitted, means whereby each set oifjselecting'relay .apparatus may-determine part ofarnalselecti'on `of* agdesired one of saidv elements tobeseleote'diin laccordance'with Whether the corrresponding!Y signal elementV is a dot or Va dash, means to completesaid finalselectiornand means whereby the per son sending any. selective signalingcode mayde feat said: final-selection after' the :lapse of-:a time period .of any lengthV `following .the last unit- ,of Y.the code. Y K Y L C 3. Inza signaling system, asignaling circuitover which various selective ,signaling vcodes each .consisting ofV the same xed numberiofunits may lbe sent,eachrcode unit being .either -a dot or ity of diierent rselections of A.elements Ato be selected by means` of a-corresponding'number of said'codes, ,saidr` selecting apparatus including a plurality of sets 0f. selecting relayapparatus, :one ,i

set for eachr code unit of'a code, 'meansresponsive to said, code units, whether/dots or dashes, to successively-'connect said fsetsofselective relay .apparatus to said `signaling circuit as successive. units of said selective signalingcode are Y materially different from that of .said units;

,Y 5. a signaling system, a signaling circuit over which various selective .signalingcodes each consisting of theAsameA-xednumberof units may be sent, keach codeunit beingfeither a dot ora dashso thatfthe total number of codes possible will .be .2, where nl is the number ofcode unitsin eacl'code', .the Vdashes [of Yeach uof said Vcodes Vbeing of an orderfof time duration materially Jdifferent 'from the usual-dashes of a Morse'code'and from a normal successionpof units of a teletypew-riter code', a selective apparatus for making a, plurality of diferent selections of elements tobe selected byJmeans of a corresponding number of said lcodes, said selecting apparatus including a plural-ity of sets of Vselectingrelay apparatus, one set for-'each code unit of acude, 4means responsive to said-code units, Whether-dots or-dashes, to successivelyconnect said sets of selectivefrelayapparatus to Vsaid signaling circuit as. successive-units of said selective signaling Acode are transmitted, means whereby'` each set .ofiselecting .relay apparatus may determine part of a nal .selection of a desired one of said elements to be selected in ac,-

Y Y cordance with4 .whether theV correspcndingsignal element is a dot or a dash, f means tocomplet'e said final selection, vmeans to condition .said sets Vof selecting relay apparatus after each signaling code has been received .-so that they Will notbe operatedby the nextY Selective signaling-Code unless-said selective signaling. 'rode is :preceded by Va circuit. .condition corresponding to. one of the units of said selective signaling code but of an order of time magnitude materially diierent from that of said urLt, and means to defeat a final selection in accordance with any selective signaling code received unless said selective signaling code is followed by a circuit condition of the same character as the units of a selective signaling code but of an order of time magnitude materially diierent from that of said units.

6. In a signaling system, a signaling circuit over which various selective signaling codes each consisting of the same fixed number of units may be sent, each code unit being either a dot or a dash so that the total number of codes possible will be 2n where n, isy the number of code units in each code, the dashes of each of said codes being of an order of time duration materially different from the usual dashes of a Morse code, a selective apparatus for making a plurality of different se lections of elements tc be selected by meansof a corresponding number of said codes, said selecting apparatus including a plurality of sets yof selecting relay apparatus, one set for each code unit of a code, means responsive to said code units, whether dots or dashes, to successively connect said sets of selective relay apparatus tc said signaling circuit as successive units of said selective signaling code are transmitted, means whereby each set of selecting relay apparatus may determine part of a iinal selection of a desired one of said elements to be selected in accordance with whether the corresponding signal element is a dot or a dash, means to complete said final selection, means to condition said sets of selecting relay apparatus after each signaling code has been received so that they will not be operated by the next selective signaling code unless said selective signaling code is preceded by a circuit condition corresponding to one of the units of said selective signaling code but of an order of time magnitude materially different from that of said unit, and means to defeat a nal selection in accordance with any selective signaling code received unless said selective signaling code is followed by a circuit condition of the same character as the units of a selective signaling code but of an order of time magnitude materially different from that of said units.

7. In a signaling system, a signaling circuit overv which various selective signaling codes each consisting of the same fixed number of units may be sent, each code unit being either a dot or a dash so that the total number of codes possible will be 2n where n is the number of code units in each code, the dashes of each of said codes beingV of an order of time duration materially different from the usual dashes of a Morse code, means comprising a teletypewriter transmitter for sending said dots and dashes, a selective apparatus for making a plurality of'diierent selections of elements to be selected by means of a corresponding number of" said codes, said selecting apparatus including a plurality' of sets of selecting relay apparatus, one set for each code unit of a code, means responsive to said code units, whether dots or dashes, to successively connect said sets of selective relay apparatus to said signaling circuit as successive units of said selective signaling code are transmitted, means whereby each set of selecting relay apparatus may determine part of a final selection of a desired one of said elements to be selected in accordance withV whether the corresponding signal element is a dot or a dash, and means to complete said final selection. Y Y

8.-In a signaling system, a signaling circuit over which various selective signaling codes each consisting of the same fixed number of units may be sent, each code unit being either a dot or a dash so that the totalnumber of codes possible will be 2n where n is the number of code units in each code, the dashes of each of said codes being of an order of time duration materially different from the usual dashes of a Morse code, means comprising a teletypewri'ter transmitter for sending said dots and dashes in the form of printer character codes, a selective apparatus for making a plurality of different selections of elements to be selected by means of a corresponding number of said codes, said selecting apparatus including a plurality of sets of selecting relay apparatus, one set for each code unit of a code, means responsive to said code units', whether dots or dashes, to successively connect said sets of selective relay apparatus to Said signaling circuit as successive units of said selective signaling code are transmitted, means whereby each setv of selecting relay apparatus may determine part of a nal selection of a desired one of said elements to be selected in accordance with whether the corresponding signal element is a dot or a dash, and means to complete said nnal selection.

JAMEs T. NEISWINTER. 

